1. Field of the Invention
This invention relates to a nozzle device for aliquoting a specimen from a test tube or some other specimen container that contains a specimen, such as blood, and dispensing the specimen into another specimen container.
2. Description of the Related Art
In a known nozzle device for aliquoting and dispensing a specimen such as blood, as is described in Jpn. Pat. Appln. KOKAI Publication No. 6-323964, for example, a nozzle portion and a dispensing tip are attached to and detached from each other with use of a balloon that can be inflated and deflated by supplying and discharging a fluid. In this aliquoting/dispensing device, a balloon is provided on the nozzle portion of a head member that is located on the distal end of a specimen supply/discharge pipe. This balloon is connected to a fluid supply/discharge pipe and configured to be inflated or deflated as the fluid is supplied or discharged. If the fluid is supplied to the balloon through the fluid supply/discharge pipe with the nozzle portion including the balloon inserted in a barrel portion at the proximal end portion of the dispensing tip, the balloon is inflated and brought intimately into contact with the inner peripheral surface of the barrel portion of the tip. If the fluid in the balloon is discharged through the fluid supply/discharge pipe, on the other hand, the balloon is deflated and separated from the inner peripheral surface of the barrel portion of the tip. Thus, the nozzle portion and the dispensing tip can be attached to and detached from each other.
In another known nozzle device, as is described in Jpn. Pat. Appln. KOKAI Publication No. 9-127130, for example, a nozzle portion and a dispensing tip are attached to and detached from each other with use of an elastic bag capable of inflation and deflation. In this nozzle device, a ring-shaped elastic bag is provided on the outer periphery of the distal end portion of a nozzle body. This elastic bag has a hollow portion through which a fluid can be supplied and discharged. If the fluid is supplied to the bag through a fluid supply/discharge pipe with the nozzle body including the bag inserted in a barrel portion at the proximal end portion of the dispensing tip, the bag is inflated and brought intimately into contact with the inner peripheral surface of the barrel portion of the tip. If the fluid in the bag is discharged through the fluid supply/discharge pipe, on the other hand, the bag is deflated and separated from the inner peripheral surface of the barrel portion of the tip. Thus, the nozzle portion and the dispensing tip can be attached to and detached from each other.
In either of the prior art examples described above, however, the balloon is inflated or deflated by supplying or discharging the fluid so that it is pressed against or separated from the inner peripheral surface of the barrel portion of the dispensing tip, whereby the nozzle portion and the tip are attached to or detached from each other. Since an additional device is needed to supply and discharge the fluid to and from the balloon, therefore, the construction of the nozzle device is complicated. While the balloon, which should be inflated and deflated, must be thin-walled, moreover, it is easily damaged by friction as it is rubbed against the inner peripheral surface of the barrel portion of the dispensing tip. Thus, the balloon requires frequent maintenance including replacement.